| In millions, except per share items | Dec-31-22 | Dec-31-21 | Dec-31-20 | Dec-31-19 | Dec-31-18 | Dec-31-17 | Dec-31-16 | Dec-31-15 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
| INVESTMENT INCOME | | | | | | | | |
| Real estate income, net: | | | | | | | | |
| |
| Real estate property level expenses and taxes: | | | | | | | | |
| Operating expenses | | | | | | | | |
| Real estate taxes | 203.7 | 208.1 | 209.2 | 187.4 | 178.9 | 166.7 | 158.7 | 144.4 |
| Interest expense | | | | | | | | -81.1 |
| |
| Total real estate property level expenses and taxes | | | | | | | | |
| Real estate income, net | | | | | | | | |
| Income from real estate joint ventures | | | | | | | | |
| Income from real estate funds | | | | | | | | |
| Interest | | | 18.0 | 23.2 | 50.8 | 26.3 | 32.5 | 10.1 |
| |
| TOTAL INVESTMENT INCOME | | | | | | | | |
| Expenses: | | | | | | | | |
| Investment management charges | | | | | | | | |
| Administrative charges | | | | | | | | |
| Distribution charges | | | | | | | | |
| Mortality and expense risk charges | | | | | | | | |
| Liquidity guarantee charges | | | | | | | | |
| Interest expense | | | | | | | | -81.1 |
| |
| TOTAL EXPENSES | | | | | | | | |
| INVESTMENT INCOME, NET | | | | | | | | |
| NET REALIZED AND UNREALIZED GAIN (LOSS) ON INVESTMENTS AND DEBT | | | | | | | | |
| Net realized gain (loss) on investments: | | | | | | | | |
| |
| Real estate joint ventures | | | | | | | | |
| Real estate funds | | | | | | | | |
| |
| Net realized gain (loss) on investments | | | | | | | | |
| Net change in unrealized gain (loss) on: | | | | | | | | |
| Real estate properties | | | | | | | | |
| Real estate joint ventures | | | | | | | | |
| Real estate funds | | | | | | | | |
| Real estate operating business | | | | | | | | |
| Foreign currency exchange on forward contracts | | | | | | | | |
| Marketable securities | | | | | | | | |
| Loans receivable | | | | | | | | |
| Loans payable | | | | | | | | |
| Other unsecured debt | | | | | | | | |
| Net change in unrealized (loss) gain on investments and debt | | | | | | | | |
| NET REALIZED AND UNREALIZED (LOSS) GAIN ON INVESTMENTS AND DEBT | | | | | | | | |
| NET (DECREASE) INCREASE IN NET ASSETS RESULTING FROM OPERATIONS | 2,335.8 | 4,206.8 | -228.0 | 1,427.0 | 1,181.6 | 1,058.4 | 1,184.9 | 1,646.4 |